The present invention relates generally to general surgery, orthopaedic implants used for insertion between an interphalangeal joint. More specifically, but not exclusively, the present invention concerns an interphalangeal implant for insertion between a patient's interphalangeal joints. Digital deformities of the fingers and toes are some of the most common conditions encountered by orthopedics and podiatrists. Patient's with digital deformities often experience significant pain from structural abnormalities. Some of these abnormalities are acquired or caused by traumatic injuries, neuromuscular pathologies, systemic diseases, or mechanical problems secondary to extrinsic pressures. The deformities are popularly known as mallet finger, jersey finger, coach's finger, hammer toe, as well as a host of other names indicative of several different pathologies.
Hammer toes is generally described as an acquired disorder, typically characterized by hyperextension of the metatarsophalangeal joint (MTP joint), hyperflexion of the proximal interphalangeal joint (PIP joint), and hyperextension of the distal interphalangeal joint (DIP joint). Although this condition can be conservatively managed through the use of orthotic devices, in certain instances surgical intervention is required.
In order to prevent recurrence of the deformity and ensure the success of the surgical procedure, a PIP joint arthrodesis is typically performed. The “end-to-end” or “peg-in-hole” techniques are the most commonly used procedures. The PIP joint is aligned with the rest of the toe in a corrected anatomical position and maintained in place by the use of a 0.045 Kirschner Wire (k-wire) which is driven across the joint. Initially, the wire is placed from the PIP joint through the tip of the toe. It is then driven in retrograde fashion into the proximal phalanx. The exposed wire exiting the toe is bent to an angle greater than 90 degrees and the bent portion is cut at approximately 1 cm from the bend. At the conclusion of the surgical procedure, a small compressive dressing is placed around the toe, with a splint being used for three to four weeks to protect the pin and the toe in order to maintain correction. The k-wire and the splint are generally removed three weeks after surgery. Similar procedures may be followed to create arthrodesis of the DIP joint of the toe or for arthrodesis performed in the finger to correct digital abnormalities of the hand.
Although this type of surgical procedure has alleviated the discomfort of hammer toe and other abnormalities of the toe and finger joints for countless patients, the use of a k-wire can result in the possible post-surgical misalignment of the phalanges caused by distraction of the k-wire, as well as swelling, inflammation, and possible infection at the site of the exposed k-wire segment.
Prosthetic devices have been used to treat deformities of the finger joints. These prosthetic devices can be inserted into adjoining phalanges of the finger and can serve to function ostensibly as a normal knuckle would. Since it is generally necessary to permit one or more of the joints of the finger to flex and bend, some of these devices are slightly angled to provide for an anatomically acceptable interphalangeal joint angle of the finger. These prosthetic devices are typically made of metallic materials with smooth surface finishes, such as, that from a machining operation and finishing or polishing. While being biocompatible and inert, many of the prosthetic devices do not provide stable enough constructs and do not have a rough enough surface to promote bone growth in and around the device allowing for arthrodesis of the PIP joint. In addition, many of the devices offer surgical techniques that are complex and difficult with many steps and multiple implant or device components for implantation.
Therefore, a need exists for a bone fixation device which overcomes the above-noted problems.